Island groups are often subject to habitat filters and dissimilar dispersal sources, and as a result may reflect dissimilar plant assemblages between islands. Though the Aleutian Islands have likely acted as a route for plant dispersal across the North Pacific, many continental endemics have colonized the islands but have not dispersed over the chain as a whole (Talbot, 1994). Typically, North American endemic plant species represent an increasing proportion of the flora with closer proximity to the Alaskan mainland, while Asian endemics increase in proportion towards Kamchatka (Lindroth, 1961). Using plant species occurrence data across the Western Aleutian Islands, we may examine the impact of several barriers to dispersal and flora assemblage.